Self-checkout system



FIG. 1 is a front, top and left side perspective view of a self-checkout system showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a right side view thereof; and,

FIG. 4 is a left side view thereof.

The broken line showing of portions of the self-checkout system is included for the purpose of illustrating environmental structure and forms no part of the claimed design.

The bottom and rear views of the self-checkout system are non-ornamental and have not been claimed. 

The ornamental design for a self-checkout system, as shown and described. 